"I just went overseas with him, I happened to go on his trip to Davos where he went over there to raise all this money for Haiti," McAuliffe said. "He never went to bed in four days. I mean we've got to get rested just to travel with President Clinton."
But though some of those traveling with Clinton say he appeared pale and tired, McAuliffe said he was in good health and good spirits.
"I have been fortunate to travel with him a lot; we went to Africa last year, and I asked him all the time, I said, 'How are you feeling?' McAuliffe said. "He said, 'Honestly I feel better now than any other time in my life.'"
Dr. Harlan Krumholz, professor of medicine at Yale University and a cardiologist at Yale-New Haven Hospital, told "Good Morning America's" Robin Roberts that Clinton's new lifestyle probably delayed the development of new heart problems following his 2004 bypass operation. Krumholz also said Clinton's reaction to his chest pain serves as a good example for others who live with heart disease.
"I think there's a lesson here for people who are listening and following this case," Krumholz said. "The thing is that heart disease is a chronic condition, and it really is important to pay attention to all these things. Prevention makes a difference, but we can't cure it."